Allen-Bradley Powerflex 70
This weekend we were called out to a large bakery who were having ongoing issues with an Allen-Bradley Powerflex 70 drive from 2004 that was overheating despite having 2 large fans and compressed air being aimed at it.
Expecting failed cooling fans or similar this was a real strange one. Monitoring the drive temperature on the keypad, when the drive was enabled the temperature climbed to over 110 degrees within around 20 seconds, despite both cooling fans running, showing a serious fundamental failure inside the drive.
We removed the drive and took it back to the workshop. Dismantling the unit showed the heatsink area to be extremely dirty, but not blocked. When the power board was removed we found a serious lack of heatsink compound, and any that remained had turned hard. We also found many capacitors open circuit around the IGBT gate drive supply section which would have caused issues with switching.
The drive was thoroughly cleaned, dried and rebuilt with fresh compound and new capacitors throughout. The IGBT was replaced as it was showing signs of heat damage and we had one in stock.
Running the drive afterwards revealed a much more expected behaviour with the temperature hardly increasing despite hot ambient temperatures. Our conclusion on this was a culmination of issues giving the fault which had slowly got worse over time.
The drive is now back to full health, meticulously clean and fully serviced, ready to run for another 20 years. The customer suffered zero downtime and resumed production at 6am as planned.
